Approach to the Patient: Hyponatremia and the Syndrome of Inappropriate Antidiuresis (SIAD)

The role of serum sodium in poor prognosis evaluation of pulmonary hypertension associated with left heart disease

BACKGROUND

Previous studies have shown that hyponatremia was strongly associated with a poor prognosis of type 1 pulmonary hypertension, and our team's antecedent studies found that low serum sodium was associated with the severity and the length of hospitalization of pulmonary hypertension associated with left ventricular disease (PH-LHD). However, the relationship between serum sodium and the prognosis of PH-LHD remains unclear. This study aims to determine the clinical value of serum sodium in evaluating poor prognosis in patients with PH-LHD.

METHODS

We successfully followed 716 patients with PH-LHD. Kaplan-Meier was used to plot survival in PH-LHD patients with different serum sodium levels. The effect of serum sodium on poor prognosis was analyzed using a Cox proportional risk model. The trends between patients serum sodium and survival were visualized by restricted cubic spline (RCS).

RESULTS

The survival rates at 1, 2, 3 and 4 years were 52%, 41%, 31% and 31% for the patients with hyponatremia associated with PH-LHD and 71%, 71%, 71% and 54% for the patients with hypernatremia, respectively. The observed mortality rate in the hyponatremia and hypernatremia groups surpassed that of the normonatremic group. The adjusted risks of death (risk ratio) for patients with hyponatremia and hypernatremia were found to be 2.044 and 1.877. Furthermore, the restricted cubic spline demonstrated an L-shaped correlation between serum sodium and all-cause mortality in patients with PH-LHD.

CONCLUSIONS

Abnormal serum sodium level is strongly associated with poor prognosis in PH-LHD. Serum sodium may play an important pathogenic role in PH-LHD occurrence and could be used as a marker to assess the survival in patients.

Comparative Safety and Effectiveness of Urea and Tolvaptan for the Management of Hyponatremia

Background: The optimal management of euvolemic and hypervolemic hyponatremia remains controversial. The effectiveness of the vasopressin receptor antagonist tolvaptan on serum sodium normalization has been well described in the literature, although the associated risk of serum sodium overcorrection limits its use. Urea has been proposed as an alternative treatment option due to its milder serum sodium raising effects and adverse event profile. Objective: This study aimed to compare urea and tolvaptan for their serum sodium raising effects and potential for overcorrection. Methods: In a multicenter retrospective review, 46 hospitalized patients who received either urea or tolvaptan for the management of hyponatremia were evaluated for the rate of serum sodium normalization and overcorrection. Results: Mean serum sodium concentrations at baseline were 125.91 mEq/L and 123.83 mEq/L for patients treated with urea and tolvaptan, respectively. After 12 hours, tolvaptan was associated with a significantly higher rate of serum sodium increase compared with urea (5.05 mEq/L vs 1.10 mEq/L; P = .001). However, no statistically significant differences were observed in the mean change in serum sodium concentrations at 24 hours, 48 hours, or with the proportion of patients who reached a serum sodium concentration of 135 mEq/L. Overcorrection rates were significantly higher with tolvaptan compared with urea at 43% and 9%, respectively. Conclusion: The results of this study suggest that urea has a comparable effectiveness profile to tolvaptan for the management of hyponatremia with a significantly reduced risk of overcorrection.

Iatrogenic adrenal insufficiency in adults

Iatrogenic adrenal insufficiency (IAI) is the most common form of adrenal insufficiency in adult patients, although its overall exact prevalence remains unclear. IAI is associated with adverse clinical outcomes, including adrenal crisis, impaired quality of life and increased mortality; therefore, it is imperative that clinicians maintain a high index of suspicion in patients at risk of IAI to facilitate timely diagnosis and appropriate management. Herein, we review the major causes, clinical consequences, diagnosis and care of patients with IAI. The management of IAI, particularly glucocorticoid-induced (or tertiary) adrenal insufficiency, can be particularly challenging, and the provision of adequate glucocorticoid replacement must be balanced against minimizing the cardiometabolic effects of excess glucocorticoid exposure and optimizing recovery of the hypothalamic-pituitary-adrenal axis. We review current treatment strategies and their limitations and discuss developments in optimizing treatment of IAI. This comprehensive Review aims to aid clinicians in identifying who is at risk of IAI, how to approach screening of at-risk populations and how to treat patients with IAI, with a focus on emergency management and prevention of an adrenal crisis.

Clinical study on the relationship between liver cirrhosis, ascites, and hyponatremia

BACKGROUND

Cirrhosis is a common liver disease, and ascites is one of the common clinical conditions. However, the clinical manifestations of ascites combined with hyponatremia as a high-risk condition and its relationship to patient prognosis have not been fully studied.

AIM

To explore the clinical manifestations, prognostic factors, and relationships of ascites with hyponatremia in patients with cirrhosis to provide better diagnostic and treatment strategies.

METHODS

In this study, we retrospectively analyzed the clinical data of 150 patients diagnosed with cirrhosis and ascites between 2017 and 2022. Patients were divided into two groups: ascites combined with hyponatremia group and ascites group. We compared the general characteristics, degree of hyponatremia, complications, treatment, and prognosis between the two groups.

RESULTS

In the study results, patients in the ascites combined with hyponatremia group showed an older average age (58.2 ± 8.9 years), 64.4% were male, and had a significantly longer hospitalization time (12.7 ± 5.3 d). Hyponatremia was more severe in this group, with a mean serum sodium concentration of 128.5 ± 4.3 mmol/L, which was significantly different from the ascites group of 137.6 ± 2.1 mmol/L. Patients with ascites and hyponatremia were more likely to develop hepatic encephalopathy (56.2% vs 39.0%), renal impairment (45.2% vs 28.6%) and infection (37.0% vs 23.4%). Regarding treatment, this group more frequently used diuretics (80.8% vs 62.3%) and salt supplements (60.3% vs 38.9%). Multiple logistic regression analysis identified older age [Odds ratio (OR) = 1.06, P = 0.025] and male gender (OR = 1.72, P = 0.020) as risk factors for hyponatremia combined with ascites. Overall, patients with ascites and hyponatremia present a clear high-risk status, accompanied by severe complications and poor prognosis.

CONCLUSION

In patients with cirrhosis, ascites with hyponatremia is a high-risk condition that is often associated with severe complications.

[Consensus recommendations on the diagnosis and treatment of hyponatremia from the Austrian Society for Nephrology 2024]

Hyponatremia is a disorder of water homeostasis. Water balance is maintained by the collaboration of renal function and cerebral structures, which regulate thirst mechanisms and secretion of the antidiuretic hormone. Measurement of serum-osmolality, urine osmolality and urine-sodium concentration help to diagnose the different reasons for hyponatremia. Hyponatremia induces cerebral edema and might lead to severe neurological symptoms, which need acute therapy. Also, mild forms of hyponatremia should be treated causally, or at least symptomatically. An inadequate fast increase of the serum sodium level should be avoided, because it raises the risk of cerebral osmotic demyelination. Basic pathophysiological knowledge is necessary to identify the different reasons for hyponatremia which need different therapeutic procedures.

Long-term low-dose tolvaptan efficacy and safety in SIADH

PURPOSE

Tolvaptan, a selective vasopressin V2-receptor antagonist, is approved for the treatment of SIADH-related hyponatremia, but its use is limited. The starting dose is usually 15 mg/day, but recent clinical experience suggests a lower starting dose (<15 mg/day) to reduce the risk of sodium overcorrection. However, long-term low-dose efficacy and safety has not been explored, so far. Aim of our study is to characterize safety and efficacy of long-term SIADH treatment with low-dose Tolvaptan.

METHODS

We retrospectively evaluated 11 patients receiving low-dose Tolvaptan (<15 mg/day) for chronic SIADH due to neurological, idiopathic and neoplastic causes. Plasma sodium levels were measured before and 1, 3, 5, 15 and 30 days after starting Tolvaptan and then at 3-month intervals. Anamnestic and clinical data were collected.

RESULTS

Mean time spanned 27.3 ± 29.8 months (range 6 months-7 years). Mean plasma sodium levels were within normal range 1, 3 and 6 months after starting Tolvaptan as well as after 1, 2, 3, 5 and 7 years of therapy. Neither osmotic demyelination syndrome nor overcorrection were observed. Plasma sodium levels normalization was associated with beneficial clinical effects. Neurological patients obtained seizures disappearance, improvement in neurological picture and good recovery from rehabilitation. Neoplastic patients were able to start chemotherapy and improved their general condition. Patients did not show hypernatremia during long-term follow-up and reported mild thirst and pollakiuria.

CONCLUSIONS

The present study shows that long-term low-dose Tolvaptan is safe and effective in SIADH treatment. No cases of overcorrection were documented and mild side effects were reported.

Syndrome of Inappropriate Antidiuresis: From Pathophysiology to Management

Hyponatremia is the most common electrolyte disorder, affecting more than 15% of patients in the hospital. Syndrome of inappropriate antidiuresis (SIAD) is the most frequent cause of hypotonic hyponatremia, mediated by nonosmotic release of arginine vasopressin (AVP, previously known as antidiuretic hormone), which acts on the renal V2 receptors to promote water retention. There are a variety of underlying causes of SIAD, including malignancy, pulmonary pathology, and central nervous system pathology. In clinical practice, the etiology of hyponatremia is frequently multifactorial and the management approach may need to evolve during treatment of a single episode. It is therefore important to regularly reassess clinical status and biochemistry, while remaining alert to potential underlying etiological factors that may become more apparent during the course of treatment. In the absence of severe symptoms requiring urgent intervention, fluid restriction (FR) is widely endorsed as the first-line treatment for SIAD in current guidelines, but there is considerable controversy regarding second-line therapy in instances where FR is unsuccessful, which occurs in around half of cases. We review the epidemiology, pathophysiology, and differential diagnosis of SIAD, and summarize recent evidence for therapeutic options beyond FR, with a focus on tolvaptan, urea, and sodium-glucose cotransporter 2 inhibitors.

A profile of SGLT-2 inhibitors in hyponatremia: The evidence to date

Hyponatremia is the most common electrolyte disorder in clinical practice, which may lead to life-threatening complications. Several lines of evidence suggest that hyponatremia is associated not only with significant increases in length of stay, cost, and financial burden, but also with increased morbidity and mortality. Hyponatremia is also considered to be a negative prognostic factor in patients with heart failure and cancer. Although multiple therapeutic methods are available for treating hyponatremia, most have some limitations, such as poor compliance, rapid correction of serum Na⁺, other negative side effects and high cost. Given these limitations, identifying novel therapies for hyponatremia is essential. Recent clinical studies have shown that SGLT-2 inhibitors (SGLT 2i) significantly increased serum Na⁺ levels and were well tolerated by patients who underwent this treatment. Therefore, oral administration of SGLT 2i appears to be an effective treatment for hyponatremia. This article will briefly review the etiology of hyponatremia and integrated control of sodium within the kidney, current therapies for hyponatremia, potential mechanisms and efficacy of SGLT 2i for hyponatremia, and the benefits in cardiovascular, cancer, and kidney disease by regulating sodium and water balance.

G protein-coupled receptors in cochlea: Potential therapeutic targets for hearing loss

The prevalence of hearing loss-related diseases caused by different factors is increasing worldwide year by year. Currently, however, the patient’s hearing loss has not been effectively improved. Therefore, there is an urgent need to adopt new treatment measures and treatment techniques to help improve the therapeutic effect of hearing loss. G protein-coupled receptors (GPCRs), as crucial cell surface receptors, can widely participate in different physiological and pathological processes, particularly play an essential role in many disease occurrences and be served as promising therapeutic targets. However, no specific drugs on the market have been found to target the GPCRs of the cochlea. Interestingly, many recent studies have demonstrated that GPCRs can participate in various pathogenic process related to hearing loss in the cochlea including heredity, noise, ototoxic drugs, cochlear structure, and so on. In this review, we comprehensively summarize the functions of 53 GPCRs known in the cochlea and their relationships with hearing loss, and highlight the recent advances of new techniques used in cochlear study including cryo-EM, AI, GPCR drug screening, gene therapy vectors, and CRISPR editing technology, as well as discuss in depth the future direction of novel GPCR-based drug development and gene therapy for cochlear hearing loss. Collectively, this review is to facilitate basic and (pre-) clinical research in this area, and provide beneficial help for emerging GPCR-based cochlear therapies.

Hyponatraemia and the syndrome of inappropriate antidiuresis (SIAD) in cancer

Hyponatraemia is a common electrolyte abnormality seen in a wide range of oncological and haematological malignancies and confers poor performance status, prolonged hospital admission and reduced overall survival, in patients with cancer. Syndrome of inappropriate antidiuresis (SIAD) is the commonest cause of hyponatraemia in malignancy and is characterised by clinical euvolaemia, low plasma osmolality and concentrated urine, with normal renal, adrenal and thyroid function. Causes of SIAD include ectopic production of vasopressin (AVP) from an underlying tumour, cancer treatments, nausea and pain. Cortisol deficiency is an important differential in the assessment of hyponatraemia, as it has an identical biochemical pattern to SIAD and is easily treatable. This is particularly relevant with the increasing use of immune checkpoint inhibitors, which can cause hypophysitis and adrenalitis, leading to cortisol deficiency. Guidelines on the management of acute, symptomatic hyponatraemia recommend 100 mL bolus of 3% saline with careful monitoring of the serum sodium to prevent overcorrection. In cases of chronic hyponatraemia, fluid restriction is recommended as first-line treatment; however, this is frequently not feasible in patients with cancer and has been shown to have limited efficacy. Vasopressin-2 receptor antagonists (vaptans) may be preferable, as they effectively increase sodium levels in SIAD and do not require fluid restriction. Active management of hyponatraemia is increasingly recognised as an important component of oncological management; correction of hyponatraemia is associated with shorter hospital stay and prolonged survival. The awareness of the impact of hyponatraemia and the positive benefits of active restoration of normonatraemia remain challenging in oncology.